Felt drying rollers and the like



Feb- 2l, W67 B. v. LECKNER 3,304,626

FELT DRYING ROLLERS AND THE LIKE Filed April 27, 1964 INVENTOR United States Patent fihce 7sjBnif'tiZ Patented Feb. 2t, 1967 ELT DRYING ROLLERS AND THE LIKE Brje Valentin Leckner, Linnegatan 20, Jonkoping, Sweden Filed Apr. 27, 1964, ser. No. 362,629 s Claims. (cl. :t4-11s) This invention relates to drying rollers, for drying felt or other web material that have channels extending longitudinally of the roller for the purpose of passing a drying medium such as air either from the inside of the roller through the part of the web in contact with the periphery of the roller or in the opposite direction from the outside through the roller periphery, whereby in the former in stance the drying medium is fed into the roller through one or both ends thereof, and in the other instance the medium is extracted at one or both of said ends of the roller.

More particularly the invention relates to a drying roller .having groove-shaped channels running longitudinally for the passage of a gaseous drying medium, and means for transferring the drying medium to or from said channels at least at one end of the roller.

Such blowing or drying rollers have been known for many decades,.and they are employed not only for drying felts but also for drying other web materials of a structure such that it can be permeated by a gaseous drying medium, usually hot air, at desired flow density without excessive permeation resistance-that is in the order of 100 mm. water column.

Other designs of blowing or drying rollers are also known, for instance, such rollers the complete interior of which constitutes either a pressure chamber o-r a suction chamber. It is evident that the web can only engage the shell of the roller periphery over a limited arc, and the device must be such, that the passage of air outside the area of contact between the roller and the web is prevented. In rollers of this type, a masking device must be provided blocking otf those sections of the perforated surface of the roller, through which air is not allowed to ass.

p In rollers with longitudinal passages or channels, the supply or extraction of air at the end of the roller is effected only for those channels momentarily embraced by the area of contact of the web. For all types of rollers of this class the supply to or extraction from the roller of the drying air involves a complicated design problem. Many different solutions of that problem have been suggested, one of which is disclosed in German patent specication No. 817,074. According to that specification the supply or extraction of the air is effected by means of a labyrinth device embracing the end of the roller. Even if such a design is functionally satisfactory, it suffers from many inconveniences, for example the necessity of special bearings for the roller and the inaccessibility of the encased roller end.

According to the present invention a simplified arrangement is attained that permits the use of ordinary bearings, as well as waist type bea-rings, which for different reasons are often preferable for rollers of this kind. The roller end remains accessible to the requisite extent; and the means for the supply or extraction of the air can easily be removed for inspection, cleaning and the like. Another feature is the particular design of that part of the roller intended for the air permeation of the felt or the like.

The invention is characterized in that radially extending plates form the channel walls the outer edges of said plates being disposed at the circumference of the roller and in that at least one longitudinal vane is interposed between eve-ry pair of adjacent channel walls, the outer edges of said vanes being disposed at the circumference of the roller.

The foregoing and other features will be fully understood from the following description of one embodiment of the invention which is illustrated on the accompanying drawings, in which FIGURE 1 shows a side elevation of a roller with parts broken away and with a waist type bearing at the left end and an ordinary bearing at the right end;

FIGURE 2 is an end view as seen from the left of FIG- URE 1;

FIGURE 3 represents a crosssection through the middle of the roller; and

FIGURE 4 is a detail of FIGURE 3 on a larger scale.

Referring to FIGURE 1 reference numeral 1 denotes the roller, which is supported by a shaft 2 provided with journalling means in the shape of a double stub shaft 27, 27 at the left end and shaped as a tube 28 within the roller. The roller has a perforated central portion 3 between two imperforate end portions 4, the latter affording contact surfaces for the edges of the felt or web for sealing purpose. The end planes 5 and 6 of the roller are parallel to each other and perpendicular to the axis of rotation. The end planes each have an outer contact ring 7' and an inner contact ring 8. Spaced plates 9 extend radially and axially or longitudinally from the tubular part of the shaft 2 to the periphery of the roller (FIG- URE 3). Between these plates intermediate vanes 10 are located which .also extend axially and the outer edges of which lie on the roller periphery. The spaces 11 between the plates 9 form channels having sector-shaped cross sections. These channels form the transport passages for the air along the length of the roller. For the purpose of stilfening the plates or walls 9 perpendicular strips 12 (FIG. 4) are inserted between every two adjacent walls, and the intermediate vanes 1d are attached to the strips. The strips 12 are perforated as at 13 to afford passages for the air. The perforations may be formed as circula-r holes as shown or as slots extending in the longitudinal direction of the roller. By selecting the number, size and distribution of the perforations, it is possible to obtain a uniform or otherwise predetermined ow of the air through a web contacting the roller. This is important especially for web materials with a low permeation resistance. For materials that have a high permeation resistance, the web itself acts as an equalizer for the flow, and for such materials the spaces 14 between the walls or plates 9 and the vanes 10 need no additional walls or strips 12, provided the ow is uniformly distributed.

The following description is restricted to a blowing type roller. (For suction rollers the conditions are reversed.) The roller with its shaft and journals is supported by the hearings 1S, the left bearing being a waist type bearing while the right one is an ordinary bearing. In other respects both ends of the roller are exactly alike, and therefore the descrip-tion can be restricted to the left part. Arrows indicate the principal air ow paths.

The air is supplied through a preferably flexible tube 1o, the end of which is connected `by a union 17 with a manifold 18. The manifold is provide-d with a sectorshaped opening 13 (see especially FIGURE 2) communicating with the channels 11 when in `front of the opening. A sealing member 19 is inserted between the side of the manifold around the opening 18 and the roller end 5. This sealing member 19 seals the space between the manifold and the roller end plane and permits the roller to rotate although the manifold is stationary. A uniform contact pressure is achieved by means of a resilient suspension of the manifold 18. A bracket 20 is rigidly fixed to the bearing housing or support and carries three internally threaded sleeves 21.

a An inner sleeve 22 is screwed into each of the sleeves 21 and accommodates a stud 23 which is rigidly secured to the manifold. A compression spring 24 in the sleeve 22 exerts pressure against the roller end through the stud 23. The contact pressure can be adjusted by screwing the sleeve 22 in or out of the sleeve 21.

The drying roller structure is preferably made of steel and assembled in the following way. Around the central tubular portion 28 of the shaft 2, in the ends of which the stub shafts 27 are pressed in, the channel partition walls 9 are welded to the tube 2S with their inner edges and distributed uniformly in a star-shaped manner. The spacing between the partition walls in the circumferential direction depends on the diameter of the roller. The greater the diameter, the smaller the circumferential spacing. An angle of about is normally adequate for rollers of ordinary size, that is having a length of SGO-500 cm. and a diameter of approximately -36 cm.

Between every two adjacent partition walls 9 the at iron strips 12 are inserted, their longitudinal edges being welded to the corresponding faces of the partition walls 9. The strips 12 should be located somewhat inside the circumference of the roller. These strips 12 welded to the partition walls 9 which are in their turn welded to the tube 28 form a rigid roller frame giving the entire roller a great strength. The strips 12 are provided with holes, slots or the like as at 13 for providing a uniform or otherwise desired distribution of the air ow. Especially when a uniform air ow along the roller is required, which is generally the case, the strips 12 ought to be sufciently retracted radially inwards from the roller circumference as to form real longitudinal grooves or spaces 14 in which the air flow can ybe finally equalized for 'a uniform drying of the web.

The intermediate vanes 10 running lengthwise in the groove-shaped spaces 14 are preferably flat steel ribs, the inner edge of which is welded to the outer face of the respective strips 12.

Alfter the entire structure has been welded together in this way, it is put up in a lathe and turned until it has Vgot the required even circular-cylindrical circumference. The aforementioned Chamfering or bevelling of the edges of the walls 9 and of the vanes 10 can be made before or after the turning of the roller structure.

When operating as a drying roller, the roller has a felt or other web 25 engaging a portion of its circumference corresponding to the sector-shaped opening 18'. The air supply means may be provided at both ends of the roller, or at one end only, depending on the length of the roller. The air flows into and along the roller through the channels 11 and out of the roller through the spaces 14 into and through the web, the tension of which has lo be sufficient to keep the web in close contact with the roller against the action of the air pressure. In the case of suction the drying medium flows, of course, in the opposite direction and the outside air presses the web against the roller.

In the embodiment illustrated the manifold 18 is annular with the shaft 2 passing through the central opening. In this instance the air supply may be provided tbelow the shaft or laterally thereof the opening 18 remaining in the place shown. If the air is supplied from above, the manifold 18 may `be limited to a sector-shaped structure surrounding the sector opening 18.

It is unavoidable that the sealing member 19 diminishes in thickness due to wear. This is compensated in the rst place by means of the spring loading and in the second place by adjustment of the sleeves 22. When required, replacement of the sealing member is easily effected. For that purpose the manifold is released by unscrewing the sleeves 22 so that the sealing member is made accessible. According to FIGURE l there is another sealing member 19 4below the shaft. This member normally has no sealing purpose but acts as a bali ance weight for the member 19; however, the second sealing member 19 may replace in case of emergency the actual sealing member 19, should the latter become damaged.

Drying rollers with longitudinal channels have previously been designed with longitudinal strips placed across the edges of the walls 9 whereby an enlarged area for the `felt is obtained compared with the design according to the drawing. At the same time, however, the fiow area of the drying air is diminished and it is indispensable to use a higher air pressure for a given quantity of air per unit of time. This 'is of less importance in such drying rollers as have a shell labyrinth for sealing. According to the invention, higher air pressures than necessary should lbe avoided, since the contact pressure Ibetween the manifold and the roller can then be kept lower, reducing the wear of the sealing member. The construction of the roller according to FIGURE 4 admits a great ratio between the injection area and the total area of the web. Chamfering of the outer edges of the walls 9 and the vanes 10 permits the said ratio to approach 1.

Many modifications are possible within the scope of the invention. For instance, the number of vanes 10 per strip 12 may be two, three or even greater, instead of one. With supply or extraction of the air at both ends of the roller the channels may fbe divided by means of a partition wall at the centre permitting individual control of the two air flows. The rings 7 and 8 may be provided with grooves, or they may be replaced by conical or other rotational surfaces or may deviate by some other shape from the end plane.

The sealing mem-ber 19 m-ay be dispensed with, provided that the end of the roller is permitted to slide directly against the manifold sector with the help of any suitable antifriction means. The subtended angle of about of the manifold sector as shown in the drawing may be modified according to local conditions and other requirements and possibilities.

When the roller rotates relatively to the stationary manifold, when the air is supplied by blow-ing, air leakage may occur at the sides of the radial edges of the manifold. This is a matter for adjustment. Not even narrow radial edges according to the drawing do, as a rule, give rise to any leakage problems. Should such a problem arise, however, it is a simple matter to widen the edges so that no passage of air can take place, not even theoretically.

If the devices for the supply or extraction of air are yprovided at both roller ends with the channels divided in the middle by means of a partition wall, it is possible to allow a certain angle of displacement Ibetween the two opposite sectors 18.

At normal rotation speeds and ordinary air velocities the position of the manifold opening 18 may be disposed symmetrically. IIf, however, the speed of the roller is high an adjustment of the position of the manifold and/ or the width of the manifold opening may be required for the purpose of compensating additional dynamic factors.

What I claim is:

1. A rotatable drying roller for drying a web, running over part of the circumference of said drying roller in engage-ment therewith, comprising in combination:

a rotatable shaft carrying said drying roller;

a .pair of journalling means for said shaft;

a duct `for the passage of hot, gaseous drying medium;

a stationary manifold into which one end of said duct opens, said manifold being located at one end of said drying roller in close juxtaposition thereto and having an opening for the passage of said drying medium in that one of its Iwalls which faces said drying roller; a plurality of axially extending walls forming part of said drying roller an-d having their inner, longitudinal edge secured to said shaft and their outer, longitudinal edge located substantially on the circumference of said roller for momentary engagement with the web while said roller rotates, said walls thus dening an equal plurality of axially extending channels which are in momentary communication with said manifold for the passage of drying medium therethrough and through the .portion of the web being in momentary engagement with the drying roller;

an equal plurality of axially extending strips, each located in an indivi-dual channel and having its longitudinal edges secured to said walls of the channel, said strips being provided with perforations of such a number, size and distribution as to ensure a predetermined distribution of the ilow of the drying medium through the web While in momentary engagement with the drying roller; and

a plurality of axially extending vanes, each vane being disposed in one o-f said channels and having its inner, longitudinal edge secured to the stri-p ylocated in its channel and its outer longitudinal edge located substantially on the circumference of said roller for momentary engagement with the web while said roller rotates.

2. A dry-ing roller as claimed in claim 1, in which the outer edges of said channel walls are chamfered.

3. A drying roller as claimed in claim 1, in which the outer edges of said vanes are chamfered.

4. A drying roller as claimed in claim 1, in which only one vane is secured to each strip.

5. A rotatable drying roller for -drying a web, running over part of the circumference of said drying roller in engagement therewith, comprising in combination a rotatable shaft carrying said drying roller, a pair of journalling means 5for said shaft, two ducts for the passage of hot, gaseous drying medium and two stationary manifolds, each manifold being in communication with a respective one of said ducts, said manifolds being located at opposite ends of said drying roller in close juxtaposition thereto and having each an opening for the passage of said drying medium in that one of its respective side walls which faces sai-d drying roller; a plurality of axially extending walls forming part of said drying roller and having their inner, longitudinal edge secured to said shaft and their outer, longitudinal edge located substantially on the circumference of said roller for momentary engagement with the web while said roller rotates, said walls thus defining an equal plurality of axially extending channels which are in momentary communication with said manifolds for the passage of drying medium therethrough and through the portion of the web -bein-g in momentary engagement with the drying roller; an equal plurality of axially extending strips, each llocated in an individual channel and having its longitudinal edges secured to said walls of the channel, said strips being provided with perforations of such a number, size and distribution as to ensure a predetermined distribution of the flow of the drying medium through the web While in momentary engagement with the -drying roller; and a plurality of axially extending vanes, each vane being disposed in one of said channels and 4having its inner, longitudinal edge secured to the strip located in its channel and its outer longitudinal edge located on the circumference of said roller for momentary engagement with the Web while said roller rotates.

References Cited by the Examiner UNITED STATES PATENTS 2,443,419 6/1948 Gould 34-109 3,057,079 10/1962 Schmidt 34-156 3,192,647 7/1965 Strube 34-122 FOREIGN PATENTS 548,741 4/ 1932 Germany.

KENNETH W. SPRAGUE, Primary Examiner. 

1. A ROTATABLE DRYING ROLLER FOR DRYING A WEB, RUNNING OVER PART OF THE CIRCUMFERENCE OF SAID DRYING ROLLER IN ENGAGEMENT THEREWITH, COMPRISING IN COMBINATION: A ROTATABLE SHAFT CARRYING SAID DRYING ROLLER; A PAIR OF JOURNALLING MEANS FOR SAID SHAFT; A DUCT FOR THE PASSAGE OF HOT, GASEOUS DRYING MEDIUM; A STATIONARY MANIFOLD INTO WHICH ONE END OF SAID DUCT OPENS, SAID MANIFOLD BEING LOCATED AT ONE END OF SAID DRYING ROLLER IN CLOSE JUXTAPOSITION THERETO AND HAVING AN OPENING FOR THE PASSAGE OF SAID DRYING MEDIUM IN THAT ONE OF ITS WALLS WHICH FACES SAID DRYING ROLLER; A PLURALITY OF AXIALLY EXTENDING WALLS FORMING PART OF SAID DRYING ROLLER AND HAVING THEIR INNER, LONGITUDINAL EDGE SECUIRED TO SAID SHAFT AND THEIR OUTER, LONGITUDINAL EDGE LOCATED SUBSTANTIALLY ON THE CIRCUMFERENCE OF SAID ROLLER FOR MOMENTARY ENGAGEMENT WITH THE WEB WHILE SAID ROLLER ROTATES, SAID WALLS THUS DEFINING AN EQUAL PLURALITY OF AXIALLY EXTENDING CHANNELS WHICH ARE IN MOMENTARY COMMUNICATION WITH SAID MANIFOLD FOR THE PASSAGE OF DRYING MEDIUM THERETHROUGH AND THROUGH THE PORTION OF THE WEB BEING IN MOMENTARY ENGAGEMENT WITH THE DRYING ROLLER; AN EQUAL PLURALITY OF AXIALLY EXTENDING STRIPS, EACH LOCATED IN AN INDIVIDUAL CHANNEL AND HAVING ITS LONGITUDINAL EDGES SECURED TO SAID WALLS OF THE CHANNEL SAID STRIPS BEING PROVIDED WITH PERFORATIONS OF SUCH A NUMBER, SIZE AND DISTRIBUTION AS TO ENSURE A PREDETERMINED DISTRIBUTION OF THE FLOW OF THE DRYING MEDIUM THROUGH THE WEB WHILE IN MOMENTARY ENGAGEMENT WITH THE DRYING ROLLER; AND A PLURALITY OF AXIALLY EXTENDING VANES, EACH VANE BEING DISPOSED IN ONE OF SAID CHANNELS AND HAVING ITS INNER, LONGITUDINAL EDGE SECURED TO THE STRIP LOCATED IN ITS CHANNEL AND ITS OUTER LONGITUDINAL EDGE LOCATED SUBSTANTIALLY ON THE CIRCUMFERENCE OF SAID ROLLER FOR MOMENTARY ENGAGEMENT WITH THE WEB WHILE SAID ROLLER ROTATES. 